Grieb currently serves as the head coach of the Sacred Heart Prep Gators football team in Atherton, California.
Grieb attended Oak Grove High School in San Jose, California, where he was a student and a three-sport athlete in football, basketball, and baseball.
With the SaberCats, he has appeared in four ArenaBowls and wins in the 2002, 2004, and 2007, although in 2002, on his way to completing an AFL regular season record 13–1 year, he was injured against the Arizona Rattlers, sustaining a season-ending broken collarbone.
John Dutton, Grieb's backup at the time, took over and continued to help lead the team to the ArenaBowl, winning it against the same Rattlers.
Grieb was given an angle of being a young man signed off the street who was pursuing his MBA, ignoring his career in arena football.
Grieb taught chemistry and biology at Gunn High School before departing for Sacred Heart Prep's head football coaching position.